Tungsten EM filaments

Manufactured in Agar Scientific’s own production facility to the highest standards using the latest advances in ceramic and metallurgical technologies.

All filaments are manufactured to a high precision in custom engineered jigs to ensure complete accuracy, giving optimum image quality and life expectancy. After manufacture filaments are pre-conditioned by “flashing” under vacuum at temperatures that are greater than the normal operating level. They are then checked for accuracy of centring. Filament assemblies with alignment screws are adjusted under a light microscope to ensure that they are ready for immediate operation in electron microscopes.

Advantages of Agar tungsten filaments:

Minimum tip radius to ensure a coherent beam
Optimum stability and maximum brightness with a longer lifetime
Fully stress relieved for enhanced lifetime
Precise dimensions for minimal alignment adjustments

There are filaments available for most current and previous makes and models of electron microscopes, including Carl Zeiss, Hitachi, JEOL, Tescan and ThermoFisher (FEI).

See also our range of Kimball Physics LaB6 cathodes as an alternative to a replacement tungsten filament.

Electron microscope type or filament base	Product number	Ceramic disc mm	Pin diameter mm	Pin pitch mm
AEI	AGA054	12.0	1.0	6.5
AmRay /AMR (except 1200 series)	AGA086	26.0	1.0	5.0
Cambridge Instruments (except S4-10)	AGA054	12.0	1.0	6.5
CamScan with AEI conversion	AGA054	12.0	1.0	6.5
CamScan with new Tescan Column	AGA047	19.8	1.0	5.0
FEI/Thermo Fisher	AGA086	26.0	1.0	5.0
Hitachi S-Type	AGA042	9.8	1,2	2.7
Hitachi with Cartridge TM series tabletop 3400N, 3700N, SU1500, SU3500	AGA042C	9.8	1.2	2.7
ISI /ABT / Topcon 2-Pin		23.4	1.2	12.0
JEOL K-Type with metal ring	AGA092	28.0	1.2	8.0
Leica	AGA054	12.0	1.0	6.5
LEO 400 and 1400 Series SEM	AGA054	12.0	1.0	6.5
LEO1450 (except AEI conversions)	AGA043X	19.8	1.0	5.0
LEO TEM	AGA043X	19.8	1.0	5.0
Philips V-Loop (PSEM500/EM200 and later)	AGA086	26.0	1.0	5.0
Tescan	AGA047	19.8	1.0	5.0
Zeiss DSM and TEM	AGA043X	19.8	1.0	5.0
Zeiss EVO	AGA054	12.0	1.0	6.5

The electron source performance table is provided to give additional information regarding the performance and requirements for different type of electron emitters. Tungsten cathodes are still used in the majority in SEMs and in general use TEMs. Improved results can be obtained with LaB6 cathodes, whereas the highest resolution can be obtained with either Schottky or cold Field Emission Sources which can only be used in suitable EMs.

Emitter Type	Thermionic	Thermionic	Schottky FE	Cold FE
Cathode Material	W	LaB6	ZrO/W (100)	W (310)
Operating Temp (K)	2700	1800	1800	300
Cathode Radius (nm)	60,000	10,000	<1000	<100
Effective Source Radius (µm)	25	10	0.015	0.0025
Emission Current Density (A/cm2)	3	30	5300	17,000
Total Emission Current (µA)	200	80	200	5
Brightness (A/cm2.sr.kV)	1×10⁴	1×10⁵	1×10⁷	2×10⁷
Maximum Probe Current (nA)	1000	1000	10	0.2
Energy Spread @ Cathode (ev)	0.59	0.4	0.31	0.26
Energy Spread @ Source Exit (eV)	1.5 – 2.5	1.3 – 2.5	0.35 – 0.7	0.3 – 0.7
Beam Noise (%)	1	1	1	5 – 10
Emission Current Drift (%/h)	0.1	0.2	<0.5	5
Operating Vacuum (hPa/mbar)	<10^-5	<10^-6	<10^-8	<10^-10
Typical Cathode Life (h)	100	>1000	>5000	>2000
Cathode Regeneration (h)	None	None	None	6-12
Sensitivity to External Influences	Minimal	Low	Low	High